US7324727B2 - Planar lightwave circuit having optical filter - Google Patents
Planar lightwave circuit having optical filter Download PDFInfo
- Publication number
- US7324727B2 US7324727B2 US11/280,059 US28005905A US7324727B2 US 7324727 B2 US7324727 B2 US 7324727B2 US 28005905 A US28005905 A US 28005905A US 7324727 B2 US7324727 B2 US 7324727B2
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- United States
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- waveguide
- width
- denotes
- planar lightwave
- lightwave circuit
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Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/1228—Tapered waveguides, e.g. integrated spot-size transformers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12004—Combinations of two or more optical elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12083—Constructional arrangements
- G02B2006/12109—Filter
Definitions
- the present invention relates to a planar light wave circuit, and more particularly to a planar lightwave circuit having an optical filter.
- FTTH Fiber-To-The-Home
- FTTx x: Premises, Home, Business, etc.
- the optical communication method for these FTTH or the FTTx networks require various types of optical transmitting and receiving devices for performing bi-directional communications.
- the optical transmitting and receiving devices used for bi-directional communications typically include detecting data after converting optical signals of the corresponding waves to electrical signals and then transmitting the data to the receiving side after the conversion of electrical data into optical signals.
- An integrated planar lightwave circuit is mainly used as the optical transmitting and receiving device. More specifically, planar lightwave circuits having wave division multiplexing or demultiplexing filters mounted thereto are being used. Recently, planar lightwave circuits equipped with optical filters having various functions have been deployed for various applications in the optical communication network.
- FIG. 1 shows a planar lightwave circuit having an optical filter.
- the planar lightwave device 100 comprises first and second waveguides 111 and 112 separated from each other, a trench 120 which separates the first waveguide 111 from the second waveguide 112 by a predetermined distance, and an optical filter 130 positioned in the trench 120 .
- the planar lightwave circuit 100 forms the first and second waveguides 111 and 112 using a lower clad, a core, and an upper clad that are sequentially stacked on the semiconductor substrate.
- the trench 120 is formed by dicing the lower clad, the core, and the upper clad, and as a result, it separates the first waveguide 111 from the second waveguide 112 by a predetermined distance.
- the optical filter 130 is positioned in the trench 120 and between the first and second waveguides 111 and 112 , and a wave division demultiplexing filter for demultiplexing the inputted optical signals is used.
- the waveguides are separated from each other by the trench, the proceeding optical signals are diffused in the trench and as a result, some of the signals fail to converge toward the other side waveguide, thereby causing insertion losses of the optical signals.
- a planar lightwave circuit using a multi-mode waveguide has been suggested as a means for restraining the generation of insertion losses.
- the multimode waveguide does not provide a sufficient coupling efficiency suitable for a real product.
- the present invention has been made to solve the above-mentioned problems occurring in the prior art and provides additional advantages, by providing a planar lightwave circuit for restraining the loss generated by mounting an optical filter.
- a planar lightwave circuit having an optical filter which includes: a first waveguide; a second waveguide separated from the first waveguide, in which the width of a first cross-section opposite to the first waveguide is narrower than that of a second cross-section of the other side; and a trench located between the first and second waveguides, in which the optical filter is positioned.
- FIG. 1 illustrates a planar lightwave circuit having a conventional optical filter
- FIG. 2 illustrates a planar lightwave circuit according to an embodiment of the present invention
- FIG. 3 is a view for showing the planar lightwave circuit shown in FIG. 2 ;
- FIG. 4 is a view for showing the planar lightwave circuit shown in FIG. 2 ;
- FIGS. 5 and 6 are graphs comparing optical signal coupling losses of the planar lightwave circuit according to the present invention with those of a conventional planar lightwave circuit.
- a planar lightwave circuit 200 includes first and second waveguides 211 and 212 , a trench 220 which separates the first waveguide from the second waveguide, and an optical filter 230 positioned in the trench 220 .
- the planar lightwave circuit 200 includes a substrate 201 , a lower clad 240 , a core( 210 ), and an upper clad( 250 ) sequentially stacked on the substrate 201 .
- the first wave guide 211 is a single mode waveguide and includes a linear transmission waveguide 221 a and a reflection waveguide 211 b .
- the reflection waveguide 211 b is identical to the second waveguide 212 .
- the transmission waveguide 211 a is a single mode waveguide and outputs the inputted optical signals to the optical filter.
- the reflection waveguide 211 b has a shape of a parabolic horn or polynomial curve and transfers the light reflected in the optical filter 230 .
- the trench 220 is formed by dicing portions of the lower clad 240 , core( 210 ), and an upper clad( 250 ), and serves to separate the second waveguide 212 from the first waveguide 211 .
- the trench is inclined by a predetermined angle a with respect to an optical axis and determined according to the relation between the optical filter 230 and the first and second waveguides 211 and 212 .
- the second waveguide 212 has a profile according to Equation 1 or Equation 2.
- the optical signals inputted through the first waveguide 211 are diffused while passing through the second waveguide 212 . Therefore, the second waveguide compensates for the insertion loss generated in the trench.
- W(t) is a function which represents the width change to the lengthwise direction parallel to the optical axis of the second waveguide 212
- L h represents the length of the second waveguide 212
- W 1 represents the width of one surface of the second waveguide 212 opposite to the first waveguide 211
- ⁇ is a shape-controlling parameter for the line width of the second waveguide 212 .
- W(t) is a function which represents width change to the lengthwise direction parallel to the optical axis of the second waveguide 212
- L h represents the length of the second waveguide 212
- W 1 represents the width of one surface of the second waveguide 212 opposite to the first waveguide 211 .
- W(t) is a polynomial function
- the second waveguide 212 has a structure in which the width thereof is gradually wider according to Equation 2.
- FIGS. 5 and 6 are graphs of a comparison of optical signal coupling losses between the planar lightwave circuit according to the present invention and a conventional planar lightwave circuit. More specifically, FIG. 5 compares the planar lightwave circuit according to the present invention with the conventional planar lightwave circuit in case a refractive index difference between the cores and the clads is 0.3%, and FIG. 6 compares the present invention and the prior art in case the refractive index difference is 0.75%.
- the trench widths of the planar lightwave circuit shown in FIGS. 5 and 6 can be variously applied with 20 to 40 ⁇ m.
- W 1 is 8 ⁇ m
- ⁇ is 0.21
- L h is 274 ⁇ m
- the profile is determined in Equation 1 and Equation 2.
- the dotted line in the graph represents the insertion loss of a planar lightwave circuit which is not according to the teachings of the present invention. It shows the insertion loss between within 0.03 to 0.06 dB.
- the solid line represents the insertion loss change of the planar lightwave circuit which includes the horn waveguide at the second waveguide according to the present invention, and the insertion loss change is between 0.01 to 0.02 dB which is a value less than 50% of the insertion loss of the dotted line.
- the graph shows the test result when W 1 is 4 ⁇ m, ⁇ is 0.78, L is 277.5 ⁇ m, and the profile is determined in Equation 1.
- the dotted line represents the insertion loss of the planar lightwave circuit which has no horn structure as in the present invention.
- the insertion loss is 0.1 dB in case the width of the trench is 20 ⁇ m, and the insertion loss is 0.25 dB in case the width of the trench is 40 ⁇ m.
- the insertion loss I is increased by 25 times compared with that of the trench having a width of 20 ⁇ m in case that the width of the trench is 40 ⁇ m.
- the solid line represents the insertion loss of the planar lightwave circuit having a horn structure according to the teachings of the present invention.
- the insertion loss is within 0.02 to 0.03 dB and is decreased by under about 1/10 compared with the case in which the planar lightwave circuit having no horn structure.
- the insertion losses of the planar lightwave circuit using the waveguide of horn structure is decreased in comparison with those of the conventional planar lightwave circuit.
- the insertion loss of the planar lightwave circuit including the waveguide of horn structure of FIG. 6 is 0.02 to 0.03 dB, and is similar to that of the planar lightwave circuit which has refractive index difference of 0.3% which is shown in FIG. 5 .
- the insertion loss of the planar lightwave circuit which comprises a waveguide of the profile according to the present invention is remarkably smaller than that of the conventional device.
- the structure of the present invention can be applied to the planar lightwave circuit having refractive index difference larger than 0.3%.
- the present invention can be applied to high density integration of the planar lightwave circuit and to an HIC (high index contrast) platform to which an optical filter is mounted.
- the insertion loss of the planar lightwave circuit which does not include a waveguide of the horn structure is largely changed according to the width of the trench
- the insertion loss of the planar lightwave circuit which includes the waveguide of the horn structure is smoothly changed regardless of the width of the trench.
- the planar lightwave circuit according to the present invention has a structure insensible to the width of the trench, and thus the width of the trench can be variously applied. Therefore, the planar lightwave circuit according to the present invention can use various types of optical filters.
- Table 1 below is a table for comparing insertion losses of the planar lightwave circuit which can perform multiplexing/demultiplexing functions in which the light of some waves are reflected and the light of some waves are transmitted.
- the insertion losses of the planar light wave circuit which has refractive index difference of 0.75% and includes waveguides with the horn structure are compared with those of the planar light wave circuit which has no horn structure.
- the planar lightwave circuit applied to Table 1 has an optical filter of multiplexing/demultiplexing type in which the light having a wave of 1310 nm can be transmitted and in which the light having a wave of 1550 nm can be reflected.
- the optical filter used in the experiment of Table 1 has a substrate whose thickness is 4 ⁇ m, and has a overall thickness of 22 ⁇ m including the thickness of a thin film.
- the transmission and reflection losses of the planar lightwave circuit of the horn structure are decreased by more than 50%, compared with the planar lightwave circuit which does not have the waveguide of horn structure.
- the overall insertion loss can be restrained.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Power Engineering (AREA)
- Optical Integrated Circuits (AREA)
Abstract
Description
W(t)=W 1+√(αtL h ),(0≦t≦1)
W(t)=W 1 +a(tL)+b(tL)2 +c(tL)3 + . . . +z(t L)n
Conventional waveguide | Waveguide with horn | ||
(refractive index | structure (refractive index | ||
difference of 0.75%) | difference of 0.75%) | ||
Transmission | ~1.0 dB | <0.5 dB |
loss (T) | ||
Reflection | ~1.2 dB | <0.8_dB |
loss (R) | ||
Claims (12)
W(t)=W 1 +√{square root over (αtL)},(0≦t≦1),
W(t)=W 1 +√{square root over (αtLh)},(0≦t≦1),
W(t)=W1 +a(tL)+b(tL)2 +c(tL)3 + . . . +z(tL) n, (0≦t≦1),
W(t)=W 1 +√{square root over (αtLh)},(0≦t≦1),
W(t)=W 1 +√{square root over (αtL)},(0≦t≦1),
W(t)=W 1 +a(tL)+b(tL)2 +c(tL)3 + . . . +z(t L)n, (0≦t≦1),
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020040093493A KR100584452B1 (en) | 2004-11-16 | 2004-11-16 | Planar lightwave circuit with optical filter |
KR2004-93493 | 2004-11-16 |
Publications (2)
Publication Number | Publication Date |
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US20060104571A1 US20060104571A1 (en) | 2006-05-18 |
US7324727B2 true US7324727B2 (en) | 2008-01-29 |
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Application Number | Title | Priority Date | Filing Date |
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US11/280,059 Active US7324727B2 (en) | 2004-11-16 | 2005-11-16 | Planar lightwave circuit having optical filter |
Country Status (2)
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US (1) | US7324727B2 (en) |
KR (1) | KR100584452B1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150168650A1 (en) * | 2012-06-13 | 2015-06-18 | Siphx Corporation | Thin film filter (tff) embedded waveguide wdm device employing parabola-shaped waveguides |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2018116115A (en) * | 2017-01-17 | 2018-07-26 | 古河電気工業株式会社 | Crossing optical waveguide structure and optical waveguide element |
KR102472213B1 (en) * | 2022-03-02 | 2022-11-30 | (주)프로 | Light assembly |
Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5799120A (en) * | 1995-12-04 | 1998-08-25 | Nec Corporation | Waveguide type wavelength multiplexing/demultiplexing module |
US5858051A (en) * | 1995-05-08 | 1999-01-12 | Toshiba Machine Co., Ltd. | Method of manufacturing optical waveguide |
US6047098A (en) * | 1997-02-07 | 2000-04-04 | Hitachi, Ltd. | Plastic optical waveguide and optical switch using same |
US6236774B1 (en) * | 1999-03-22 | 2001-05-22 | Gemfire Corporation | Optoelectronic and photonic devices formed of materials which inhibit degradation and failure |
US6243516B1 (en) * | 1998-02-23 | 2001-06-05 | Fujitsu Limited | Merging optical waveguides having branch angle within a specific range |
US6434318B1 (en) * | 2000-08-02 | 2002-08-13 | Gemfire Corporation | Device and method for variable attenuation of an optical channel |
US6579398B1 (en) * | 1999-07-13 | 2003-06-17 | Sony Corporation | Method of manufacturing optical waveguide |
US20040228573A1 (en) * | 2003-05-15 | 2004-11-18 | Yukari Terakawa | Optical multiplexer/demultiplexer |
US7039289B1 (en) * | 2000-05-19 | 2006-05-02 | Optinetrics, Inc. | Integrated optic devices and processes for the fabrication of integrated optic devices |
US7065269B2 (en) * | 2003-07-11 | 2006-06-20 | Omron Corporation | Optical multiplexer/demultiplexer, optical integrated circuit and light transceiver using the same |
US20060165373A1 (en) * | 2002-11-12 | 2006-07-27 | Xponent Photonics Inc | Optical component for free-space optical propagation between waveguides |
US7103252B2 (en) * | 2001-10-25 | 2006-09-05 | Fujitsu Limited | Optical waveguide and fabricating method thereof |
-
2004
- 2004-11-16 KR KR1020040093493A patent/KR100584452B1/en not_active IP Right Cessation
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2005
- 2005-11-16 US US11/280,059 patent/US7324727B2/en active Active
Patent Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5858051A (en) * | 1995-05-08 | 1999-01-12 | Toshiba Machine Co., Ltd. | Method of manufacturing optical waveguide |
US5799120A (en) * | 1995-12-04 | 1998-08-25 | Nec Corporation | Waveguide type wavelength multiplexing/demultiplexing module |
US6047098A (en) * | 1997-02-07 | 2000-04-04 | Hitachi, Ltd. | Plastic optical waveguide and optical switch using same |
US6243516B1 (en) * | 1998-02-23 | 2001-06-05 | Fujitsu Limited | Merging optical waveguides having branch angle within a specific range |
US6236774B1 (en) * | 1999-03-22 | 2001-05-22 | Gemfire Corporation | Optoelectronic and photonic devices formed of materials which inhibit degradation and failure |
US6579398B1 (en) * | 1999-07-13 | 2003-06-17 | Sony Corporation | Method of manufacturing optical waveguide |
US7039289B1 (en) * | 2000-05-19 | 2006-05-02 | Optinetrics, Inc. | Integrated optic devices and processes for the fabrication of integrated optic devices |
US6434318B1 (en) * | 2000-08-02 | 2002-08-13 | Gemfire Corporation | Device and method for variable attenuation of an optical channel |
US7103252B2 (en) * | 2001-10-25 | 2006-09-05 | Fujitsu Limited | Optical waveguide and fabricating method thereof |
US20060165373A1 (en) * | 2002-11-12 | 2006-07-27 | Xponent Photonics Inc | Optical component for free-space optical propagation between waveguides |
US20040228573A1 (en) * | 2003-05-15 | 2004-11-18 | Yukari Terakawa | Optical multiplexer/demultiplexer |
US7065269B2 (en) * | 2003-07-11 | 2006-06-20 | Omron Corporation | Optical multiplexer/demultiplexer, optical integrated circuit and light transceiver using the same |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150168650A1 (en) * | 2012-06-13 | 2015-06-18 | Siphx Corporation | Thin film filter (tff) embedded waveguide wdm device employing parabola-shaped waveguides |
Also Published As
Publication number | Publication date |
---|---|
KR20060053449A (en) | 2006-05-22 |
US20060104571A1 (en) | 2006-05-18 |
KR100584452B1 (en) | 2006-05-26 |
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